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Diffstat (limited to 'Documentation/w1')
| -rw-r--r-- | Documentation/w1/index.rst | 21 | ||||
| -rw-r--r-- | Documentation/w1/masters/ds2482.rst | 39 | ||||
| -rw-r--r-- | Documentation/w1/masters/ds2490.rst | 72 | ||||
| -rw-r--r-- | Documentation/w1/masters/index.rst | 14 | ||||
| -rw-r--r-- | Documentation/w1/masters/mxc-w1.rst | 17 | ||||
| -rw-r--r-- | Documentation/w1/masters/omap-hdq.rst | 54 | ||||
| -rw-r--r-- | Documentation/w1/masters/w1-gpio.rst | 47 | ||||
| -rw-r--r-- | Documentation/w1/slaves/index.rst | 16 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_ds2406.rst | 27 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_ds2413.rst | 59 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_ds2423.rst | 54 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_ds2438.rst | 86 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_ds28e04.rst | 41 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_ds28e17.rst | 72 | ||||
| -rw-r--r-- | Documentation/w1/slaves/w1_therm.rst | 144 | ||||
| -rw-r--r-- | Documentation/w1/w1-generic.rst | 133 | ||||
| -rw-r--r-- | Documentation/w1/w1-netlink.rst | 202 |
17 files changed, 1098 insertions, 0 deletions
diff --git a/Documentation/w1/index.rst b/Documentation/w1/index.rst new file mode 100644 index 0000000000..156279f175 --- /dev/null +++ b/Documentation/w1/index.rst @@ -0,0 +1,21 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================ +1-Wire Subsystem +================ + +.. toctree:: + :maxdepth: 1 + + + w1-generic.rst + w1-netlink.rst + masters/index + slaves/index + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/w1/masters/ds2482.rst b/Documentation/w1/masters/ds2482.rst new file mode 100644 index 0000000000..17ebe8f660 --- /dev/null +++ b/Documentation/w1/masters/ds2482.rst @@ -0,0 +1,39 @@ +==================== +Kernel driver ds2482 +==================== + +Supported chips: + + * Maxim DS2482-100, Maxim DS2482-800 + + Prefix: 'ds2482' + + Addresses scanned: None + + Datasheets: + + - http://datasheets.maxim-ic.com/en/ds/DS2482-100.pdf + - http://datasheets.maxim-ic.com/en/ds/DS2482-800.pdf + +Author: Ben Gardner <bgardner@wabtec.com> + + +Description +----------- + +The Maxim/Dallas Semiconductor DS2482 is a I2C device that provides +one (DS2482-100) or eight (DS2482-800) 1-wire busses. + + +General Remarks +--------------- + +Valid addresses are 0x18, 0x19, 0x1a, and 0x1b. + +However, the device cannot be detected without writing to the i2c bus, so no +detection is done. You should instantiate the device explicitly. + +:: + + $ modprobe ds2482 + $ echo ds2482 0x18 > /sys/bus/i2c/devices/i2c-0/new_device diff --git a/Documentation/w1/masters/ds2490.rst b/Documentation/w1/masters/ds2490.rst new file mode 100644 index 0000000000..842e7ae804 --- /dev/null +++ b/Documentation/w1/masters/ds2490.rst @@ -0,0 +1,72 @@ +==================== +Kernel driver ds2490 +==================== + +Supported chips: + + * Maxim DS2490 based + +Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru> + + +Description +----------- + +The Maxim/Dallas Semiconductor DS2490 is a chip +which allows to build USB <-> W1 bridges. + +DS9490(R) is a USB <-> W1 bus master device +which has 0x81 family ID integrated chip and DS2490 +low-level operational chip. + +Notes and limitations. + +- The weak pullup current is a minimum of 0.9mA and maximum of 6.0mA. +- The 5V strong pullup is supported with a minimum of 5.9mA and a + maximum of 30.4 mA. (From DS2490.pdf) +- The hardware will detect when devices are attached to the bus on the + next bus (reset?) operation, however only a message is printed as + the core w1 code doesn't make use of the information. Connecting + one device tends to give multiple new device notifications. +- The number of USB bus transactions could be reduced if w1_reset_send + was added to the API. The name is just a suggestion. It would take + a write buffer and a read buffer (along with sizes) as arguments. + The ds2490 block I/O command supports reset, write buffer, read + buffer, and strong pullup all in one command, instead of the current + 1 reset bus, 2 write the match rom command and slave rom id, 3 block + write and read data. The write buffer needs to have the match rom + command and slave rom id prepended to the front of the requested + write buffer, both of which are known to the driver. +- The hardware supports normal, flexible, and overdrive bus + communication speeds, but only the normal is supported. +- The registered w1_bus_master functions don't define error + conditions. If a bus search is in progress and the ds2490 is + removed it can produce a good amount of error output before the bus + search finishes. +- The hardware supports detecting some error conditions, such as + short, alarming presence on reset, and no presence on reset, but the + driver doesn't query those values. +- The ds2490 specification doesn't cover short bulk in reads in + detail, but my observation is if fewer bytes are requested than are + available, the bulk read will return an error and the hardware will + clear the entire bulk in buffer. It would be possible to read the + maximum buffer size to not run into this error condition, only extra + bytes in the buffer is a logic error in the driver. The code should + match reads and writes as well as data sizes. Reads and + writes are serialized and the status verifies that the chip is idle + (and data is available) before the read is executed, so it should + not happen. +- Running x86_64 2.6.24 UHCI under qemu 0.9.0 under x86_64 2.6.22-rc6 + with a OHCI controller, ds2490 running in the guest would operate + normally the first time the module was loaded after qemu attached + the ds2490 hardware, but if the module was unloaded, then reloaded + most of the time one of the bulk out or in, and usually the bulk in + would fail. qemu sets a 50ms timeout and the bulk in would timeout + even when the status shows data available. A bulk out write would + show a successful completion, but the ds2490 status register would + show 0 bytes written. Detaching qemu from the ds2490 hardware and + reattaching would clear the problem. usbmon output in the guest and + host did not explain the problem. My guess is a bug in either qemu + or the host OS and more likely the host OS. + +03-06-2008 David Fries <David@Fries.net> diff --git a/Documentation/w1/masters/index.rst b/Documentation/w1/masters/index.rst new file mode 100644 index 0000000000..4442a98850 --- /dev/null +++ b/Documentation/w1/masters/index.rst @@ -0,0 +1,14 @@ +. SPDX-License-Identifier: GPL-2.0 + +===================== +1-wire Master Drivers +===================== + +.. toctree:: + :maxdepth: 1 + + ds2482 + ds2490 + mxc-w1 + omap-hdq + w1-gpio diff --git a/Documentation/w1/masters/mxc-w1.rst b/Documentation/w1/masters/mxc-w1.rst new file mode 100644 index 0000000000..334f989310 --- /dev/null +++ b/Documentation/w1/masters/mxc-w1.rst @@ -0,0 +1,17 @@ +==================== +Kernel driver mxc_w1 +==================== + +Supported chips: + + * Freescale MX27, MX31 and probably other i.MX SoCs + + Datasheets: + + - http://www.freescale.com/files/32bit/doc/data_sheet/MCIMX31.pdf?fpsp=1 + - http://cache.freescale.com/files/dsp/doc/archive/MCIMX27.pdf?fsrch=1&WT_TYPE=Data%20Sheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation + +Author: + + Originally based on Freescale code, prepared for mainline by + Sascha Hauer <s.hauer@pengutronix.de> diff --git a/Documentation/w1/masters/omap-hdq.rst b/Documentation/w1/masters/omap-hdq.rst new file mode 100644 index 0000000000..5347b5d9e9 --- /dev/null +++ b/Documentation/w1/masters/omap-hdq.rst @@ -0,0 +1,54 @@ +======================================== +Kernel driver for omap HDQ/1-wire module +======================================== + +Supported chips: +================ +HDQ/1-wire controller on the TI OMAP 2430/3430 platforms. + +A useful link about HDQ basics: +=============================== +http://focus.ti.com/lit/an/slua408a/slua408a.pdf + +Description: +============ +The HDQ/1-Wire module of TI OMAP2430/3430 platforms implement the hardware +protocol of the master functions of the Benchmark HDQ and the Dallas +Semiconductor 1-Wire protocols. These protocols use a single wire for +communication between the master (HDQ/1-Wire controller) and the slave +(HDQ/1-Wire external compliant device). + +A typical application of the HDQ/1-Wire module is the communication with battery +monitor (gas gauge) integrated circuits. + +The controller supports operation in both HDQ and 1-wire mode. The essential +difference between the HDQ and 1-wire mode is how the slave device responds to +initialization pulse.In HDQ mode, the firmware does not require the host to +create an initialization pulse to the slave.However, the slave can be reset by +using an initialization pulse (also referred to as a break pulse).The slave +does not respond with a presence pulse as it does in the 1-Wire protocol. + +Remarks: +======== +The driver (drivers/w1/masters/omap_hdq.c) supports the HDQ mode of the +controller. In this mode, as we can not read the ID which obeys the W1 +spec(family:id:crc), a module parameter can be passed to the driver which will +be used to calculate the CRC and pass back an appropriate slave ID to the W1 +core. + +By default the master driver and the BQ slave i/f +driver(drivers/w1/slaves/w1_bq27000.c) sets the ID to 1. +Please note to load both the modules with a different ID if required, but note +that the ID used should be same for both master and slave driver loading. + +e.g:: + + insmod omap_hdq.ko W1_ID=2 + insmod w1_bq27000.ko F_ID=2 + +The driver also supports 1-wire mode. In this mode, there is no need to +pass slave ID as parameter. The driver will auto-detect slaves connected +to the bus using SEARCH_ROM procedure. 1-wire mode can be selected by +setting "ti,mode" property to "1w" in DT (see +Documentation/devicetree/bindings/w1/omap-hdq.txt for more details). +By default driver is in HDQ mode. diff --git a/Documentation/w1/masters/w1-gpio.rst b/Documentation/w1/masters/w1-gpio.rst new file mode 100644 index 0000000000..1523660550 --- /dev/null +++ b/Documentation/w1/masters/w1-gpio.rst @@ -0,0 +1,47 @@ +===================== +Kernel driver w1-gpio +===================== + +Author: Ville Syrjala <syrjala@sci.fi> + + +Description +----------- + +GPIO 1-wire bus master driver. The driver uses the GPIO API to control the +wire and the GPIO pin can be specified using GPIO machine descriptor tables. +It is also possible to define the master using device tree, see +Documentation/devicetree/bindings/w1/w1-gpio.yaml + + +Example (mach-at91) +------------------- + +:: + + #include <linux/gpio/machine.h> + #include <linux/w1-gpio.h> + + static struct gpiod_lookup_table foo_w1_gpiod_table = { + .dev_id = "w1-gpio", + .table = { + GPIO_LOOKUP_IDX("at91-gpio", AT91_PIN_PB20, NULL, 0, + GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN), + }, + }; + + static struct w1_gpio_platform_data foo_w1_gpio_pdata = { + .ext_pullup_enable_pin = -EINVAL, + }; + + static struct platform_device foo_w1_device = { + .name = "w1-gpio", + .id = -1, + .dev.platform_data = &foo_w1_gpio_pdata, + }; + + ... + at91_set_GPIO_periph(foo_w1_gpio_pdata.pin, 1); + at91_set_multi_drive(foo_w1_gpio_pdata.pin, 1); + gpiod_add_lookup_table(&foo_w1_gpiod_table); + platform_device_register(&foo_w1_device); diff --git a/Documentation/w1/slaves/index.rst b/Documentation/w1/slaves/index.rst new file mode 100644 index 0000000000..d0697b202f --- /dev/null +++ b/Documentation/w1/slaves/index.rst @@ -0,0 +1,16 @@ +. SPDX-License-Identifier: GPL-2.0 + +==================== +1-wire Slave Drivers +==================== + +.. toctree:: + :maxdepth: 1 + + w1_ds2406 + w1_ds2413 + w1_ds2423 + w1_ds2438 + w1_ds28e04 + w1_ds28e17 + w1_therm diff --git a/Documentation/w1/slaves/w1_ds2406.rst b/Documentation/w1/slaves/w1_ds2406.rst new file mode 100644 index 0000000000..d3e6826608 --- /dev/null +++ b/Documentation/w1/slaves/w1_ds2406.rst @@ -0,0 +1,27 @@ +======================= +w1_ds2406 kernel driver +======================= + +Supported chips: + + * Maxim DS2406 (and other family 0x12) addressable switches + +Author: Scott Alfter <scott@alfter.us> + +Description +----------- + +The w1_ds2406 driver allows connected devices to be switched on and off. +These chips also provide 128 bytes of OTP EPROM, but reading/writing it is +not supported. In TSOC-6 form, the DS2406 provides two switch outputs and +can be provided with power on a dedicated input. In TO-92 form, it provides +one output and uses parasitic power only. + +The driver provides two sysfs files. state is readable; it gives the +current state of each switch, with PIO A in bit 0 and PIO B in bit 1. The +driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to +work with. output is writable; bits 0 and 1 control PIO A and B, +respectively. Bits 2-7 are ignored, so it's safe to write ASCII data. + +CRCs are checked on read and write. Failed checks cause an I/O error to be +returned. On a failed write, the switch status is not changed. diff --git a/Documentation/w1/slaves/w1_ds2413.rst b/Documentation/w1/slaves/w1_ds2413.rst new file mode 100644 index 0000000000..c15bb5b919 --- /dev/null +++ b/Documentation/w1/slaves/w1_ds2413.rst @@ -0,0 +1,59 @@ +======================= +Kernel driver w1_ds2413 +======================= + +Supported chips: + + * Maxim DS2413 1-Wire Dual Channel Addressable Switch + +supported family codes: + + ================ ==== + W1_FAMILY_DS2413 0x3A + ================ ==== + +Author: Mariusz Bialonczyk <manio@skyboo.net> + +Description +----------- + +The DS2413 chip has two open-drain outputs (PIO A and PIO B). +Support is provided through the sysfs files "output" and "state". + +Reading state +------------- +The "state" file provides one-byte value which is in the same format as for +the chip PIO_ACCESS_READ command (refer the datasheet for details): + +======== ============================================================= +Bit 0: PIOA Pin State +Bit 1: PIOA Output Latch State +Bit 2: PIOB Pin State +Bit 3: PIOB Output Latch State +Bit 4-7: Complement of Bit 3 to Bit 0 (verified by the kernel module) +======== ============================================================= + +This file is readonly. + +Writing output +-------------- +You can set the PIO pins using the "output" file. +It is writable, you can write one-byte value to this sysfs file. +Similarly the byte format is the same as for the PIO_ACCESS_WRITE command: + +======== ====================================== +Bit 0: PIOA +Bit 1: PIOB +Bit 2-7: No matter (driver will set it to "1"s) +======== ====================================== + + +The chip has some kind of basic protection against transmission errors. +When reading the state, there is a four complement bits. +The driver is checking this complement, and when it is wrong then it is +returning I/O error. + +When writing output, the master must repeat the PIO Output Data byte in +its inverted form and it is waiting for a confirmation. +If the write is unsuccessful for three times, the write also returns +I/O error. diff --git a/Documentation/w1/slaves/w1_ds2423.rst b/Documentation/w1/slaves/w1_ds2423.rst new file mode 100644 index 0000000000..755d659ad9 --- /dev/null +++ b/Documentation/w1/slaves/w1_ds2423.rst @@ -0,0 +1,54 @@ +Kernel driver w1_ds2423 +======================= + +Supported chips: + + * Maxim DS2423 based counter devices. + +supported family codes: + + =============== ==== + W1_THERM_DS2423 0x1D + =============== ==== + +Author: Mika Laitio <lamikr@pilppa.org> + +Description +----------- + +Support is provided through the sysfs w1_slave file. Each opening and +read sequence of w1_slave file initiates the read of counters and ram +available in DS2423 pages 12 - 15. + +Result of each page is provided as an ASCII output where each counter +value and associated ram buffer is outpputed to own line. + +Each lines will contain the values of 42 bytes read from the counter and +memory page along the crc=YES or NO for indicating whether the read operation +was successful and CRC matched. +If the operation was successful, there is also in the end of each line +a counter value expressed as an integer after c= + +Meaning of 42 bytes represented is following: + + - 1 byte from ram page + - 4 bytes for the counter value + - 4 zero bytes + - 2 bytes for crc16 which was calculated from the data read since the previous crc bytes + - 31 remaining bytes from the ram page + - crc=YES/NO indicating whether read was ok and crc matched + - c=<int> current counter value + +example from the successful read:: + + 00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2 + 00 02 00 00 00 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2 + 00 29 c6 5d 18 00 00 00 00 04 37 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=408798761 + 00 05 00 00 00 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=YES c=5 + +example from the read with crc errors:: + + 00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2 + 00 02 00 00 22 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=NO + 00 e1 61 5d 19 00 00 00 00 df 0b 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=NO + 00 05 00 00 20 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=NO diff --git a/Documentation/w1/slaves/w1_ds2438.rst b/Documentation/w1/slaves/w1_ds2438.rst new file mode 100644 index 0000000000..4fa671fbc9 --- /dev/null +++ b/Documentation/w1/slaves/w1_ds2438.rst @@ -0,0 +1,86 @@ +Kernel driver w1_ds2438 +======================= + +Supported chips: + + * Maxim DS2438 Smart Battery Monitor + +supported family codes: + ================ ==== + W1_FAMILY_DS2438 0x26 + ================ ==== + +Author: Mariusz Bialonczyk <manio@skyboo.net> + +Description +----------- + +The DS2438 chip provides several functions that are desirable to carry in +a battery pack. It also has a 40 bytes of nonvolatile EEPROM. +Because the ability of temperature, current and voltage measurement, the chip +is also often used in weather stations and applications such as: rain gauge, +wind speed/direction measuring, humidity sensing, etc. + +Current support is provided through the following sysfs files (all files +except "iad" and "offset" are readonly): + +"iad" +----- +This file controls the 'Current A/D Control Bit' (IAD) in the +Status/Configuration Register. +Writing a zero value will clear the IAD bit and disables the current +measurements. +Writing value "1" is setting the IAD bit (enables the measurements). +The IAD bit is enabled by default in the DS2438. + +When writing to sysfs file bits 2-7 are ignored, so it's safe to write ASCII. +An I/O error is returned when there is a problem setting the new value. + +"page0" +------- +This file provides full 8 bytes of the chip Page 0 (00h). +This page contains the most frequently accessed information of the DS2438. +Internally when this file is read, the additional CRC byte is also obtained +from the slave device. If it is correct, the 8 bytes page data are passed +to userspace, otherwise an I/O error is returned. + +"page1" +------- +This file provides full 8 bytes of the chip Page 1 (01h). +This page contains the ICA, elapsed time meter and current offset data of the DS2438. +Internally when this file is read, the additional CRC byte is also obtained +from the slave device. If it is correct, the 8 bytes page data are passed +to userspace, otherwise an I/O error is returned. + +"offset" +-------- +This file controls the 2-byte Offset Register of the chip. +Writing a 2-byte value will change the Offset Register, which changes the +current measurement done by the chip. Changing this register to the two's complement +of the current register while forcing zero current through the load will calibrate +the chip, canceling offset errors in the current ADC. + + +"temperature" +------------- +Opening and reading this file initiates the CONVERT_T (temperature conversion) +command of the chip, afterwards the temperature is read from the device +registers and provided as an ASCII decimal value. + +Important: The returned value has to be divided by 256 to get a real +temperature in degrees Celsius. + +"vad", "vdd" +------------ +Opening and reading this file initiates the CONVERT_V (voltage conversion) +command of the chip. + +Depending on a sysfs filename a different input for the A/D will be selected: + +vad: + general purpose A/D input (VAD) +vdd: + battery input (VDD) + +After the voltage conversion the value is returned as decimal ASCII. +Note: To get a volts the value has to be divided by 100. diff --git a/Documentation/w1/slaves/w1_ds28e04.rst b/Documentation/w1/slaves/w1_ds28e04.rst new file mode 100644 index 0000000000..b12b118890 --- /dev/null +++ b/Documentation/w1/slaves/w1_ds28e04.rst @@ -0,0 +1,41 @@ +======================== +Kernel driver w1_ds28e04 +======================== + +Supported chips: + + * Maxim DS28E04-100 4096-Bit Addressable 1-Wire EEPROM with PIO + +supported family codes: + + ================= ==== + W1_FAMILY_DS28E04 0x1C + ================= ==== + +Author: Markus Franke, <franke.m@sebakmt.com> <franm@hrz.tu-chemnitz.de> + +Description +----------- + +Support is provided through the sysfs files "eeprom" and "pio". CRC checking +during memory accesses can optionally be enabled/disabled via the device +attribute "crccheck". The strong pull-up can optionally be enabled/disabled +via the module parameter "w1_strong_pullup". + +Memory Access + + A read operation on the "eeprom" file reads the given amount of bytes + from the EEPROM of the DS28E04. + + A write operation on the "eeprom" file writes the given byte sequence + to the EEPROM of the DS28E04. If CRC checking mode is enabled only + fully aligned blocks of 32 bytes with valid CRC16 values (in bytes 30 + and 31) are allowed to be written. + +PIO Access + + The 2 PIOs of the DS28E04-100 are accessible via the "pio" sysfs file. + + The current status of the PIO's is returned as an 8 bit value. Bit 0/1 + represent the state of PIO_0/PIO_1. Bits 2..7 do not care. The PIO's are + driven low-active, i.e. the driver delivers/expects low-active values. diff --git a/Documentation/w1/slaves/w1_ds28e17.rst b/Documentation/w1/slaves/w1_ds28e17.rst new file mode 100644 index 0000000000..e2d9f96d8f --- /dev/null +++ b/Documentation/w1/slaves/w1_ds28e17.rst @@ -0,0 +1,72 @@ +======================== +Kernel driver w1_ds28e17 +======================== + +Supported chips: + + * Maxim DS28E17 1-Wire-to-I2C Master Bridge + +supported family codes: + + ================= ==== + W1_FAMILY_DS28E17 0x19 + ================= ==== + +Author: Jan Kandziora <jjj@gmx.de> + + +Description +----------- +The DS28E17 is a Onewire slave device which acts as an I2C bus master. + +This driver creates a new I2C bus for any DS28E17 device detected. I2C buses +come and go as the DS28E17 devices come and go. I2C slave devices connected to +a DS28E17 can be accessed by the kernel or userspace tools as if they were +connected to a "native" I2C bus master. + + +An udev rule like the following:: + + SUBSYSTEM=="i2c-dev", KERNEL=="i2c-[0-9]*", ATTRS{name}=="w1-19-*", \ + SYMLINK+="i2c-$attr{name}" + +may be used to create stable /dev/i2c- entries based on the unique id of the +DS28E17 chip. + + +Driver parameters are: + +speed: + This sets up the default I2C speed a DS28E17 get configured for as soon + it is connected. The power-on default of the DS28E17 is 400kBaud, but + chips may come and go on the Onewire bus without being de-powered and + as soon the "w1_ds28e17" driver notices a freshly connected, or + reconnected DS28E17 device on the Onewire bus, it will re-apply this + setting. + + Valid values are 100, 400, 900 [kBaud]. Any other value means to leave + alone the current DS28E17 setting on detect. The default value is 100. + +stretch: + This sets up the default stretch value used for freshly connected + DS28E17 devices. It is a multiplier used on the calculation of the busy + wait time for an I2C transfer. This is to account for I2C slave devices + which make heavy use of the I2C clock stretching feature and thus, the + needed timeout cannot be pre-calculated correctly. As the w1_ds28e17 + driver checks the DS28E17's busy flag in a loop after the precalculated + wait time, it should be hardly needed to tweak this setting. + + Leave it at 1 unless you get ETIMEDOUT errors and a "w1_slave_driver + 19-00000002dbd8: busy timeout" in the kernel log. + + Valid values are 1 to 9. The default is 1. + + +The driver creates sysfs files /sys/bus/w1/devices/19-<id>/speed and +/sys/bus/w1/devices/19-<id>/stretch for each device, preloaded with the default +settings from the driver parameters. They may be changed anytime. In addition a +directory /sys/bus/w1/devices/19-<id>/i2c-<nnn> for the I2C bus master sysfs +structure is created. + + +See https://github.com/ianka/w1_ds28e17 for even more information. diff --git a/Documentation/w1/slaves/w1_therm.rst b/Documentation/w1/slaves/w1_therm.rst new file mode 100644 index 0000000000..6aec04dd09 --- /dev/null +++ b/Documentation/w1/slaves/w1_therm.rst @@ -0,0 +1,144 @@ +====================== +Kernel driver w1_therm +====================== + +Supported chips: + + * Maxim ds18*20 based temperature sensors. + * Maxim ds1825 based temperature sensors. + * GXCAS GX20MH01 temperature sensor. + * Maxim MAX31850 thermoelement interface. + +Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru> + + +Description +----------- + +w1_therm provides basic temperature conversion for ds18*20, ds28ea00, GX20MH01 +and MAX31850 devices. + +Supported family codes: + +==================== ==== +W1_THERM_DS18S20 0x10 +W1_THERM_DS1822 0x22 +W1_THERM_DS18B20 0x28 +W1_THERM_DS1825 0x3B +W1_THERM_DS28EA00 0x42 +==================== ==== + +Support is provided through the sysfs entry ``w1_slave``. Each open and +read sequence will initiate a temperature conversion, then provide two +lines of ASCII output. The first line contains the nine hex bytes +read along with a calculated crc value and YES or NO if it matched. +If the crc matched the returned values are retained. The second line +displays the retained values along with a temperature in millidegrees +Centigrade after t=. + +Alternatively, temperature can be read using ``temperature`` sysfs, it +returns only the temperature in millidegrees Centigrade. + +A bulk read of all devices on the bus could be done writing ``trigger`` +to ``therm_bulk_read`` entry at w1_bus_master level. This will +send the convert command to all devices on the bus, and if parasite +powered devices are detected on the bus (and strong pullup is enabled +in the module), it will drive the line high during the longer conversion +time required by parasited powered device on the line. Reading +``therm_bulk_read`` will return 0 if no bulk conversion pending, +-1 if at least one sensor still in conversion, 1 if conversion is complete +but at least one sensor value has not been read yet. Result temperature is +then accessed by reading the ``temperature`` entry of each device, which +may return empty if conversion is still in progress. Note that if a bulk +read is sent but one sensor is not read immediately, the next access to +``temperature`` on this device will return the temperature measured at the +time of issue of the bulk read command (not the current temperature). + +A strong pullup will be applied during the conversion if required. + +``conv_time`` is used to get current conversion time (read), and +adjust it (write). A temperature conversion time depends on the device type and +its current resolution. Default conversion time is set by the driver according +to the device datasheet. A conversion time for many original device clones +deviate from datasheet specs. There are three options: 1) manually set the +correct conversion time by writing a value in milliseconds to ``conv_time``; 2) +auto measure and set a conversion time by writing ``1`` to +``conv_time``; 3) use ``features`` to enable poll for conversion +completion. Options 2, 3 can't be used in parasite power mode. To get back to +the default conversion time write ``0`` to ``conv_time``. + +Writing a resolution value (in bits) to ``w1_slave`` will change the +precision of the sensor for the next readings. Allowed resolutions are defined by +the sensor. Resolution is reset when the sensor gets power-cycled. + +To store the current resolution in EEPROM, write ``0`` to ``w1_slave``. +Since the EEPROM has a limited amount of writes (>50k), this command should be +used wisely. + +Alternatively, resolution can be read or written using the dedicated +``resolution`` entry on each device, if supported by the sensor. + +Some non-genuine DS18B20 chips are fixed in 12-bit mode only, so the actual +resolution is read back from the chip and verified. + +Note: Changing the resolution reverts the conversion time to default. + +The write-only sysfs entry ``eeprom_cmd`` is an alternative for EEPROM operations. +Write ``save`` to save device RAM to EEPROM. Write ``restore`` to restore EEPROM +data in device RAM. + +``ext_power`` entry allows checking the power state of each device. Reads +``0`` if the device is parasite powered, ``1`` if the device is externally powered. + +Sysfs ``alarms`` allow read or write TH and TL (Temperature High an Low) alarms. +Values shall be space separated and in the device range (typical -55 degC +to 125 degC). Values are integer as they are store in a 8bit register in +the device. Lowest value is automatically put to TL. Once set, alarms could +be search at master level. + +The module parameter strong_pullup can be set to 0 to disable the +strong pullup, 1 to enable autodetection or 2 to force strong pullup. +In case of autodetection, the driver will use the "READ POWER SUPPLY" +command to check if there are pariste powered devices on the bus. +If so, it will activate the master's strong pullup. +In case the detection of parasite devices using this command fails +(seems to be the case with some DS18S20) the strong pullup can +be force-enabled. + +If the strong pullup is enabled, the master's strong pullup will be +driven when the conversion is taking place, provided the master driver +does support the strong pullup (or it falls back to a pullup +resistor). The DS18b20 temperature sensor specification lists a +maximum current draw of 1.5mA and that a 5k pullup resistor is not +sufficient. The strong pullup is designed to provide the additional +current required. + +The DS28EA00 provides an additional two pins for implementing a sequence +detection algorithm. This feature allows you to determine the physical +location of the chip in the 1-wire bus without needing pre-existing +knowledge of the bus ordering. Support is provided through the sysfs +``w1_seq``. The file will contain a single line with an integer value +representing the device index in the bus starting at 0. + +``features`` sysfs entry controls optional driver settings per device. +Insufficient power in parasite mode, line noise and insufficient conversion +time may lead to conversion failure. Original DS18B20 and some clones allow for +detection of invalid conversion. Write bit mask ``1`` to ``features`` to enable +checking the conversion success. If byte 6 of scratchpad memory is 0xC after +conversion and temperature reads 85.00 (powerup value) or 127.94 (insufficient +power), the driver returns a conversion error. Bit mask ``2`` enables poll for +conversion completion (normal power only) by generating read cycles on the bus +after conversion starts. In parasite power mode this feature is not available. +Feature bit masks may be combined (OR). More details in +Documentation/ABI/testing/sysfs-driver-w1_therm + +GX20MH01 device shares family number 0x28 with DS18*20. The device is generally +compatible with DS18B20. Added are lowest 2\ :sup:`-5`, 2\ :sup:`-6` temperature +bits in Config register; R2 bit in Config register enabling 13 and 14 bit +resolutions. The device is powered up in 14-bit resolution mode. The conversion +times specified in the datasheet are too low and have to be increased. The +device supports driver features ``1`` and ``2``. + +MAX31850 device shares family number 0x3B with DS1825. The device is generally +compatible with DS1825. The higher 4 bits of Config register read all 1, +indicating 15, but the device is always operating in 14-bit resolution mode. diff --git a/Documentation/w1/w1-generic.rst b/Documentation/w1/w1-generic.rst new file mode 100644 index 0000000000..96a042585f --- /dev/null +++ b/Documentation/w1/w1-generic.rst @@ -0,0 +1,133 @@ +========================================= +Introduction to the 1-wire (w1) subsystem +========================================= + +The 1-wire bus is a simple master-slave bus that communicates via a single +signal wire (plus ground, so two wires). + +Devices communicate on the bus by pulling the signal to ground via an open +drain output and by sampling the logic level of the signal line. + +The w1 subsystem provides the framework for managing w1 masters and +communication with slaves. + +All w1 slave devices must be connected to a w1 bus master device. + +Example w1 master devices: + + - DS9490 usb device + - W1-over-GPIO + - DS2482 (i2c to w1 bridge) + - Emulated devices, such as a RS232 converter, parallel port adapter, etc + + +What does the w1 subsystem do? +------------------------------ + +When a w1 master driver registers with the w1 subsystem, the following occurs: + + - sysfs entries for that w1 master are created + - the w1 bus is periodically searched for new slave devices + +When a device is found on the bus, w1 core tries to load the driver for its family +and check if it is loaded. If so, the family driver is attached to the slave. +If there is no driver for the family, default one is assigned, which allows to perform +almost any kind of operations. Each logical operation is a transaction +in nature, which can contain several (two or one) low-level operations. +Let's see how one can read EEPROM context: +1. one must write control buffer, i.e. buffer containing command byte +and two byte address. At this step bus is reset and appropriate device +is selected using either W1_SKIP_ROM or W1_MATCH_ROM command. +Then provided control buffer is being written to the wire. +2. reading. This will issue reading eeprom response. + +It is possible that between 1. and 2. w1 master thread will reset bus for searching +and slave device will be even removed, but in this case 0xff will +be read, since no device was selected. + + +W1 device families +------------------ + +Slave devices are handled by a driver written for a family of w1 devices. + +A family driver populates a struct w1_family_ops (see w1_family.h) and +registers with the w1 subsystem. + +Current family drivers: + +w1_therm + - (ds18?20 thermal sensor family driver) + provides temperature reading function which is bound to ->rbin() method + of the above w1_family_ops structure. + +w1_smem + - driver for simple 64bit memory cell provides ID reading method. + +You can call above methods by reading appropriate sysfs files. + + +What does a w1 master driver need to implement? +----------------------------------------------- + +The driver for w1 bus master must provide at minimum two functions. + +Emulated devices must provide the ability to set the output signal level +(write_bit) and sample the signal level (read_bit). + +Devices that support the 1-wire natively must provide the ability to write and +sample a bit (touch_bit) and reset the bus (reset_bus). + +Most hardware provides higher-level functions that offload w1 handling. +See struct w1_bus_master definition in w1.h for details. + + +w1 master sysfs interface +------------------------- + +========================= ===================================================== +<xx-xxxxxxxxxxxx> A directory for a found device. The format is + family-serial +bus (standard) symlink to the w1 bus +driver (standard) symlink to the w1 driver +w1_master_add (rw) manually register a slave device +w1_master_attempts (ro) the number of times a search was attempted +w1_master_max_slave_count (rw) maximum number of slaves to search for at a time +w1_master_name (ro) the name of the device (w1_bus_masterX) +w1_master_pullup (rw) 5V strong pullup 0 enabled, 1 disabled +w1_master_remove (rw) manually remove a slave device +w1_master_search (rw) the number of searches left to do, + -1=continual (default) +w1_master_slave_count (ro) the number of slaves found +w1_master_slaves (ro) the names of the slaves, one per line +w1_master_timeout (ro) the delay in seconds between searches +w1_master_timeout_us (ro) the delay in microseconds between searches +========================= ===================================================== + +If you have a w1 bus that never changes (you don't add or remove devices), +you can set the module parameter search_count to a small positive number +for an initially small number of bus searches. Alternatively it could be +set to zero, then manually add the slave device serial numbers by +w1_master_add device file. The w1_master_add and w1_master_remove files +generally only make sense when searching is disabled, as a search will +redetect manually removed devices that are present and timeout manually +added devices that aren't on the bus. + +Bus searches occur at an interval, specified as a sum of timeout and +timeout_us module parameters (either of which may be 0) for as long as +w1_master_search remains greater than 0 or is -1. Each search attempt +decrements w1_master_search by 1 (down to 0) and increments +w1_master_attempts by 1. + +w1 slave sysfs interface +------------------------ + +=================== ============================================================ +bus (standard) symlink to the w1 bus +driver (standard) symlink to the w1 driver +name the device name, usually the same as the directory name +w1_slave (optional) a binary file whose meaning depends on the + family driver +rw (optional) created for slave devices which do not have + appropriate family driver. Allows to read/write binary data. +=================== ============================================================ diff --git a/Documentation/w1/w1-netlink.rst b/Documentation/w1/w1-netlink.rst new file mode 100644 index 0000000000..be4f7b82dc --- /dev/null +++ b/Documentation/w1/w1-netlink.rst @@ -0,0 +1,202 @@ +=============================================== +Userspace communication protocol over connector +=============================================== + +Message types +============= + +There are three types of messages between w1 core and userspace: + +1. Events. They are generated each time a new master or slave device + is found either due to automatic or requested search. +2. Userspace commands. +3. Replies to userspace commands. + + +Protocol +======== + +:: + + [struct cn_msg] - connector header. + Its length field is equal to size of the attached data + [struct w1_netlink_msg] - w1 netlink header. + __u8 type - message type. + W1_LIST_MASTERS + list current bus masters + W1_SLAVE_ADD/W1_SLAVE_REMOVE + slave add/remove events + W1_MASTER_ADD/W1_MASTER_REMOVE + master add/remove events + W1_MASTER_CMD + userspace command for bus master + device (search/alarm search) + W1_SLAVE_CMD + userspace command for slave device + (read/write/touch) + __u8 status - error indication from kernel + __u16 len - size of data attached to this header data + union { + __u8 id[8]; - slave unique device id + struct w1_mst { + __u32 id; - master's id + __u32 res; - reserved + } mst; + } id; + + [struct w1_netlink_cmd] - command for given master or slave device. + __u8 cmd - command opcode. + W1_CMD_READ - read command + W1_CMD_WRITE - write command + W1_CMD_SEARCH - search command + W1_CMD_ALARM_SEARCH - alarm search command + W1_CMD_TOUCH - touch command + (write and sample data back to userspace) + W1_CMD_RESET - send bus reset + W1_CMD_SLAVE_ADD - add slave to kernel list + W1_CMD_SLAVE_REMOVE - remove slave from kernel list + W1_CMD_LIST_SLAVES - get slaves list from kernel + __u8 res - reserved + __u16 len - length of data for this command + For read command data must be allocated like for write command + __u8 data[0] - data for this command + + +Each connector message can include one or more w1_netlink_msg with +zero or more attached w1_netlink_cmd messages. + +For event messages there are no w1_netlink_cmd embedded structures, +only connector header and w1_netlink_msg structure with "len" field +being zero and filled type (one of event types) and id: +either 8 bytes of slave unique id in host order, +or master's id, which is assigned to bus master device +when it is added to w1 core. + +Currently replies to userspace commands are only generated for read +command request. One reply is generated exactly for one w1_netlink_cmd +read request. Replies are not combined when sent - i.e. typical reply +messages looks like the following:: + + [cn_msg][w1_netlink_msg][w1_netlink_cmd] + cn_msg.len = sizeof(struct w1_netlink_msg) + + sizeof(struct w1_netlink_cmd) + + cmd->len; + w1_netlink_msg.len = sizeof(struct w1_netlink_cmd) + cmd->len; + w1_netlink_cmd.len = cmd->len; + +Replies to W1_LIST_MASTERS should send a message back to the userspace +which will contain list of all registered master ids in the following +format:: + + cn_msg (CN_W1_IDX.CN_W1_VAL as id, len is equal to sizeof(struct + w1_netlink_msg) plus number of masters multiplied by 4) + w1_netlink_msg (type: W1_LIST_MASTERS, len is equal to + number of masters multiplied by 4 (u32 size)) + id0 ... idN + +Each message is at most 4k in size, so if number of master devices +exceeds this, it will be split into several messages. + +W1 search and alarm search commands. + +request:: + + [cn_msg] + [w1_netlink_msg type = W1_MASTER_CMD + id is equal to the bus master id to use for searching] + [w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH] + +reply:: + + [cn_msg, ack = 1 and increasing, 0 means the last message, + seq is equal to the request seq] + [w1_netlink_msg type = W1_MASTER_CMD] + [w1_netlink_cmd cmd = W1_CMD_SEARCH or W1_CMD_ALARM_SEARCH + len is equal to number of IDs multiplied by 8] + [64bit-id0 ... 64bit-idN] + +Length in each header corresponds to the size of the data behind it, so +w1_netlink_cmd->len = N * 8; where N is number of IDs in this message. +Can be zero. + +:: + + w1_netlink_msg->len = sizeof(struct w1_netlink_cmd) + N * 8; + cn_msg->len = sizeof(struct w1_netlink_msg) + + sizeof(struct w1_netlink_cmd) + + N*8; + +W1 reset command:: + + [cn_msg] + [w1_netlink_msg type = W1_MASTER_CMD + id is equal to the bus master id to use for searching] + [w1_netlink_cmd cmd = W1_CMD_RESET] + + +Command status replies +====================== + +Each command (either root, master or slave with or without w1_netlink_cmd +structure) will be 'acked' by the w1 core. Format of the reply is the same +as request message except that length parameters do not account for data +requested by the user, i.e. read/write/touch IO requests will not contain +data, so w1_netlink_cmd.len will be 0, w1_netlink_msg.len will be size +of the w1_netlink_cmd structure and cn_msg.len will be equal to the sum +of the sizeof(struct w1_netlink_msg) and sizeof(struct w1_netlink_cmd). +If reply is generated for master or root command (which do not have +w1_netlink_cmd attached), reply will contain only cn_msg and w1_netlink_msg +structures. + +w1_netlink_msg.status field will carry positive error value +(EINVAL for example) or zero in case of success. + +All other fields in every structure will mirror the same parameters in the +request message (except lengths as described above). + +Status reply is generated for every w1_netlink_cmd embedded in the +w1_netlink_msg, if there are no w1_netlink_cmd structures, +reply will be generated for the w1_netlink_msg. + +All w1_netlink_cmd command structures are handled in every w1_netlink_msg, +even if there were errors, only length mismatch interrupts message processing. + + +Operation steps in w1 core when new command is received +======================================================= + +When new message (w1_netlink_msg) is received w1 core detects if it is +master or slave request, according to w1_netlink_msg.type field. +Then master or slave device is searched for. +When found, master device (requested or those one on where slave device +is found) is locked. If slave command is requested, then reset/select +procedure is started to select given device. + +Then all requested in w1_netlink_msg operations are performed one by one. +If command requires reply (like read command) it is sent on command completion. + +When all commands (w1_netlink_cmd) are processed master device is unlocked +and next w1_netlink_msg header processing started. + + +Connector [1] specific documentation +==================================== + +Each connector message includes two u32 fields as "address". +w1 uses CN_W1_IDX and CN_W1_VAL defined in include/linux/connector.h header. +Each message also includes sequence and acknowledge numbers. +Sequence number for event messages is appropriate bus master sequence number +increased with each event message sent "through" this master. +Sequence number for userspace requests is set by userspace application. +Sequence number for reply is the same as was in request, and +acknowledge number is set to seq+1. + + +Additional documentation, source code examples +============================================== + +1. Documentation/driver-api/connector.rst +2. http://www.ioremap.net/archive/w1 + + This archive includes userspace application w1d.c which uses + read/write/search commands for all master/slave devices found on the bus. |